The present disclosure relates to a metal line pattern of a semiconductor device and a method of forming the metal line pattern.
Generally, a semiconductor device manufactured using a silicon substrate includes an element for storing and processing data and a line pattern for inputting or outputting signals to and from the element. Aluminum and aluminum alloys are most widely used in process for manufacturing line patterns in semiconductor devices since they have excellent electric conductivity, excellent adhesive force to an oxide layer, and relatively easy processing.
In a typical metal line pattern forming method, a metal layer is formed on a substrate, and a passivation layer is formed on the metal layer to prevent the metal layer from being oxidized. A photoresist pattern is formed on the passivation layer, and the passivation layer and the metal layer are etched using the photoresist pattern as an etching mask to form the metal line pattern.
However, as design rules for the metal line pattern have been recently significantly attenuated, an alignment error of the photoresist pattern for forming the metal line pattern has frequently occurred. It is essential to accurately align the photoresist pattern on/over the metal layer.
When the photoresist pattern is misaligned, the photoresist pattern can be removed using an oxygen plasma or etchant, and a new photoresist pattern is formed on the metal layer. However, when the photoresist pattern is newly formed on the metal layer, an oxide layer may also be formed on the passivation layer. Particularly, when the passivation layer is formed of Ti or TiN, an undesirable oxide layer is formed on the passivation layer.
Hexamethyldisilazane (HMDS) may be formed on the oxide layer of the passivation layer. At this point, due to non-uniformity in the oxide layer, the HMDS is not uniformly formed on/over the passivation layer. As a result, when the photoresist pattern is re-formed on the passivation layer having the oxide layer thereon, the new photoresist pattern may collapse (or fall down sideward) before etching the metal layer. This causes the metal line pattern not to be accurately formed.